B. Vinay Kumar

DNA binding, photoactivated DNA cleavage and cytotoxic activity of Cu(II) and Co(II) based Schiff-base azo photosensitizers

A new class of Cu(II) and Co(II) complexes of azo-containing Schiff base of the type [Cu(L1)2] and [Co(L1)2], where L1=4-[(E)-{2-hydroxy-3-[(E)-(4-bromophenyl)diazenyl]benzylidene}amino]benzoic acid have been synthesized and characterized. Extension of conjugation and the presence of free carboxylic acid group of the ligand L1 increased the wavelength of the complexes from visible region to the near IR region (620-850 nm). The Cu(II) and Co(II) complexes interacted with CT-DNA via intercalative mode with the respective Kb value of 3.2×10(4) M(-1) and 2.9×10(4) M(-1) and acted as proficient photocleavers of SC pUC19 DNA in UV-A light, forming (1)O2 as the reactive oxygen species with the quantum yield of 0.38 and 0.36, respectively. Furthermore, the Cu(II) and Co(II) complexes showed photocytotoxicity toward two selected tumor cell lines MCF-7 and A549 by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) method, and the Cu(II) complex exhibits higher photocytotoxicity than Co(II) complex against each of the selected cell lines, this result is identical with their DNA binding ability order.

In Vivo prophylactic effects of oleanolic acid isolated from chloroform extract of Flaveria trinervia against ethanol induced liver toxicity in rats

The prophylactic effects of oleanolic acid (OA) isolated from chloroform extract (CE) of Flaveria trinervia against ethanol induced liver toxicity was investigated using rats. CE and OA at three different doses were tested by administering orally to the ethanol treated animals during the last week of the 7 weeks study. Silymarin was used as the standard reference. The substantially elevated serum enzymatic levels of serum glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, alkaline phosphatase and bilirubin in ethanol treated animals were restored towards normalcy by treatment of CE and OA. In vivo antioxidant and in vitro free radical scavenging activities were also positive for all the three concentrations of CE and OA. However, OA at 150 mg/kg showed significant activity when compared to the other two doses. Biochemical observations in support with histopathological examinations revealed that CE and OA possess hepatoprotective action against ethanol induced hepatotoxicity in rats.

Metal Complexes of New Tetraazamacrocyclic Constrained Oxadiazole Ring as Subunits: Synthesis, DNA Binding and Photonuclease Activity

A new tetraazamacrocyclic ligand, L (C24H16N12O6) and its complexes of type, [MLCl2] and [CuL]Cl2 (Where M = Co(II), Fe(II); L = N,N′-(benzene-1,3-diyldi-1,3,4-oxadiazole-5,2-diyl)bis{2-[(5-benzene-1,3-diyl-1,3,4-oxadiazol-2-yl)amino]acetamide}) were synthesized and characterized by elemental analysis including IR, 1H NMR, 13C NMR, mass and electronic spectral data. An octahedral geometry has been proposed for Fe(II) and Co(II) complexes except the Cu(II) complex which have a square planar environment. The binding property of the complexes with CT-DNA was studied by absorption spectra, viscosity measurement and thermal denaturation studies. The absorption spectral results indicate that the complexes binds with the base pairs of DNA with an intrinsic binding constant Kb of Cu(II), Co(II) and Fe(II) complexes were found to be 4.5 × 104 M−1, 5.7 × 104 M−1 and 2.6 × 104 M−1, respectively in 5 mM Tris-HCl/50 mM NaCl buffer at pH 7.2. The photo induced cleavage studies revealed that the complexes show photonuclease property against pUC19 DNA under UV-visible irradiation.

Benzo[h]quinoline based Macrocyclic Copper(II), Cobalt(II) Complexes: Synthesis, Characterization and Light induced DNA Cleavage Studies

A new ligand dibenzo[h]quinolineno[1,3,7,9] tetraazacyclododecine-7,15 (14H, 16H)-dibenzene (L) and its Co(II)/Cu(II) metal complexes of type [MLX2] (Where (M = Co(II) (5), Cu(II) (6) and X = Cl) were synthesized and are well characterized by FT-IR, 1H-NMR, FAB mass elemental analysis, and electronic spectral data. The role of the cobalt/copper metals in photo-induced DNA cleavage reactions was explored by designing complex molecules having macrocyclic structure. Finally, we have shown that photocleavage of plasmid DNA is more efficiently enhanced when this macrocyclic ligand is irradiated in the presence of copper(II) than that of cobalt metal.

Antibacterial, Molecular Docking, DNA Binding and Photocleavage Studies on Novel Heterocyclic Pyrazoles

The antibacterial activity, in-silico DNA molecular docking, DNA binding and photo cleavage studies of newly synthesized pyrazole is described. Antibacterial potential of these compounds screened against a wide range of Gram-positive and Gram-negative bacteria showed significant zone of inhibition and MIC with standard drug ciproflaxin is investigated. Among all the orientation of binding, fourth orientation showed significant binding and revealed that the binding and docking energy of 4a was -8.62 and -8.66 and inhibition constant 7.46 X e -6 . The absorption spectra showed the dynamic interaction with CT DNA and as proficient DNA intercalator (Kb = 4.5×10 4 M -1 ). The viscosity measurements and thermal denaturation affords the positive results towards DNA intercalation in both the studies. The light induced DNA damage was pragmatic in the absence of various ‘‘inhibitors’’ shows in photo cleavage activities at 360 nm.

Synthesis and Biological Evaluation of New Tetra-aza Macrocyclic Scaffold Constrained Oxadiazole, Thiadiazole and Triazole Rings

A new series of N,N′‐(benzene‐1,3‐diyldi‐1,3,4‐oxadiazole‐5,2‐diyl)bis{2‐[(5‐benzene‐1,3‐diyl‐1,3,4‐oxadiazol‐2‐yl)amino]acetamide}(macrocycle 1), N,N′‐(benzene‐1,3‐diyldi‐1,3,4‐thiadiazole‐5,2‐diyl)bis{2‐[(5‐benzene‐1,3‐diyl‐1,3,4‐thiadiazol‐2‐yl)amino]acetamide} (macrocycle 2) and S,S′‐[benzene‐1,3‐diylbis(4H‐1,2,4‐triazole‐5,3‐diyl)]bis{[(5‐benzene‐1,3‐diyl‐4H‐1,2,4‐triazol‐3‐yl)sulfanyl]ethanethioate}(macrocycle 3) was synthesized from isophthalic dihydrazide (4) through a multistep reaction sequence. All the synthesized compounds were screened for their inhibitory effect against four different bacterial strains: P. aeruginosa ATCC‐20852, K. pneumoniae MTCC‐618, S. aureus ATCC‐ 29737, S. typhi MTCC‐ 3214. The synthesized compounds showed a significant zone of inhibition and the results were comparable with that of the standard drug ciprofloxacin. The synthesized compounds were further studied for their possible in vitro antioxidant effects by DPPH scavenging, total antioxidant capacity, total reductive capacity and H2O2 scavenging activity. The results indicated that the in vitro antioxidant activity for all the three molecules was efficient when compared to the standards. The DNA interaction behavior of macrocycles 1–3 with CT‐DNA was investigated by the absorption spectra obtained (Kb constant for 1 is 4.53 × 104 M−1, for 2 is 5.75 × 104 M−1 and for 3 is 5.86 × 104 M−1). Based on the results it can be interpreted that the reducing power effect of the newly synthesized compounds demonstrates a direct effect on DNA binding and hence inhibiting the bacterial growth through their action on DNA by inhibiting DNA replication or DNA transcription.

Synthesis of Functionalized Iron Oxide Nanoparticle with Amino Pyridine Moiety and Studies on Their Catalytic Behavior

Aim: The main objective of this paper is to study the synthesis of functionalized iron oxide nanoparticle and its reactivity towards chromene synthesis Study design: Functionalized iron oxide nanoparticle study. Place and duration of study: Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta, between December 2009 and July 2010. Methodology: This paper describes synthesis of stable functionalized iron oxide nanoparticles through surface modification of magnetic iron oxide nanoparticles by amino pyridine. Iron oxide nanoparticles were synthesized by co-precipitation method and the surface modification process was achieved by treating the nanoparticles with (chloro propyl trimethoxy silane) CPTS and aminopyridine. The developed functionalized iron oxide nanoparticle was evaluated as the catalyst for synthesis of chromones under MW irradiation conditions. Results: The catalysts were magnetically recovered and reusable without significant loss of their catalytic efficiency. To receive morphological and structural information on the obtained functionalized nanoparticle, the samples were analyzed by X-ray diffraction (XRD) measurements, FTIR and scanning electron microscopy (SEM) imaging. All synthesized chromene derivatives were characterized using analytical techniques such as IR, H NMR, and mass spectroscopy. Also the identity of these compounds was easily established by comparison of their melting point with those of reported samples. Conclusion: In summary, we have developed a new magnetically recyclable and Research Article American Chemical Science Journal, 1(3): 97-108, 2011 98 efficient functionalized magnetic nano catalyst for the chromene synthesis. Magnetic nanoparticle catalyst achieves a simple separation of catalyst without filtration including high yield in product.

Synthesis, DNA Binding, and Photonuclease Activity of New Tetraaza Macrocyclic Constrained Isoxazole Rings as Subunit in Metal Complexes

The DNA-binding and photonuclease activity of newly synthesized tetra-azamacrocyclic ligand L (C32H32N8O4) and its complexes of type [MLCl2] and [ML]Cl2 (where M = Co(II), Fe(II) and Cu(II); L = N,N′-[3-(4-{5-[(2-amino-ethylamino)-methyl]-isoxazol-3yl}-phenyl)-isoxazol-5-yl methyl-ethane-1,2-diamine] are specified. An octahedral geometry has been proposed for Fe(II) and Co(II) complexes, while the Cu(II) complex has a square planar environment. The absorption spectral results indicate that the complexes bind with the base pairs of DNA, with an intrinsic binding constant Kb of Fe(II), Co(II), and Cu(II) complexes found to be 3.2 × 104 M−1, 5.3 × 104 M−1, and 4.2 × 104 M−1, respectively, in 5 mM Tris-HCl/50 mM NaCl buffer at pH 7.2. The large enhancement in the relative viscosity of DNA on binding to the complexes supports the proposed DNA binding modes. The viscosity and thermal denaturation studies sustain the effective intercalation with DNA. The DNA photocleavage studies demonstrated that compounds exhibit significant photonuclease activity by a concentration dependent on singlet oxygen mediated mechanism.